title: The effects of topical sodium cromoglicate on itch and flare in human skin induced by intradermal histamine: a randomised double-blind vehicle controlled intra-subject design trial.
abstract: BACKGROUND
  Itch is a prominent feature of many skin diseases, particularly atopic dermatitis and cutaneous mastocytosis. Sodium cromoglicate (SCG), a chromone developed for the treatment of allergic disease has been shown to reduce the severity of itch when applied topically to subjects with atopic dermatitis. The aim of this study was to investigate whether topical sodium cromoglicate can reduce the severity of itch induced by intradermal histamine.
  
  
  METHODS
  SCG was introduced into the skin of healthy volunteers both by iontophoresis and by topical application using a new 4% cutaneous emulsion (Altoderm™). The skin was then challenged with intradermal histamine. Measurements were made of severity of itch, size of wheal and flare and change in blood flux
  
  
  RESULTS
  SCG significantly reduced the severity of itch (P = 0.0045) and flare (P = 0.0143) when delivered by iontophoresis. SCG 4% cutaneous emulsion significantly reduced severity of itch (P = 0.024) and flare (P = 0.015) in atopic subjects. Trend analysis showed increasing effect on itch with increased concentrations of SCG, which was significant (P = 0.046). There were no effects on wheal or blood flux.
  
  
  CONCLUSIONS
  Topically applied SCG, administered in a new cutaneous emulsion base, significantly reduced the itch and flare caused by intradermal histamine. The effect was greatest in atopic subjects and increased with the concentration of SCG in the emulsion.
  
  
  BACKGROUND
  ISRCTN35671014.
authors.affiliation: The David Hide Asthma and Allergy Research Centre, St Mary's Hospital, Newport, PO30 5TG, Isle of Wight, UK. dramedwards@btinternet.com.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Edwards
authors.forename: Michael T
authors.initials: MT
authors.lastname: Stevens
authors.forename: Martin K
authors.initials: MK
authors.lastname: Church